The present invention relates in general to sensor devices for biomedical monitoring of electrocardiogram or EKG signals from human subjects without attachment to the subjects of any leads or sensor devices, and more particularly to sensor devices constructed in pad form on which a human subject may sit or on which a part of the body of the human subject may rest which requires no power source but is capable of obtaining EKG signals from the subject transmitted to the sensor device through the medium of the subject's perspiration to provide EKG signals appropriate for monitoring the subject's heart action, especially usable to record EKG signals or sense EKG signals in such way that sudden serious heart failure of persons such as aircraft pilots can be immediately recognized and an alarm generated.
Intermittently, pilots in command of aircraft are struck with incapacitation due to pain, heart failure, seizure or other medical disorders. In almost all cases except for sudden seizure and sudden heart failure, the pilot has time to request assistance from the co-pilot or other aircraft personnel and ask the co-pilot to take over. In attacks of sudden serious heart failure, the pilot is not capable ordinarily of warning the co-pilot due to the way he loses consciousness.
With the increasing number and age of airline pilots, inadvertently some of them have died of heart failure while on active duty in the cockpit. Over the past years, incidents of sudden incapacitation due to heart failure among aircraft pilots actually flying planes have increased. With the increase in number and the advancing age of the commercial airline pilot population, this increase was to be expected. Over the past ten years or so, at least three pilots a year have met sudden incapacitation due to coronary heart failure and death while in command of passenger-carrying commercial aircraft. It is believed that about fifteen pilots have died from sudden heart failure while in charge of a commercial airliner in the final phase of the landing procedure. It is during the final phase of the landing procedure when the co-pilot is most busy with radio communication, notes, checklists, and other tasks and therefore least likely to be instantly aware of the pilot's difficulty. During such landing approaches with modern jet aircraft, the five to fifteen seconds which might pass before the co-pilot realizes the situation and can take over is often such that it is then too late for him to be effective.
To combat these serious problems, it is desirable to have means by which the EKG of the pilot may be continuously monitored so that electronic instruments receiving the EKG signals may sense when pilot heart failure may be occurring and alert the co-pilot by an alarm so that he will be prepared to take over in the event of sudden heart failure and instant incapacitation of the pilot. Since it is impractical in airline operations, and often impossible, to attach leads to the pilot for biomedical monitoring such as monitoring the EKG of the pilot, it is desirable to develop suitable ways to obtain such biomedical signals from the pilot so as to provide a good quality EKG from the pilot with no immediate preflight preparation of the pilot and without attachment of any special electrodes or sensors of any type to the pilot's body. Also it is important to avoid electrical leads or connections to any part of the pilot's wearing apparel such as might restrict or interfere with the pilot's mobility, performance and/or comfort.
Also, it is desirable in other situations to be able to monitor the EKG of a human subject in other circumstances without having to attach any sensors or monitoring devices to the body or clothing of the subject. For example, it is highly desirable in many cases to be able to monitor the EKG signals of a patient being transported on a stretcher or under similar circumstances where connections to fixed heart monitoring installations may not be readily accessible to provide an alarm or record of the subject's EKG during transportation of the subject.
An object of the present invention, therefore, is the provision of a novel sensor device in pad form for obtaining EKG signals from human subjects without attachment of any leads or devices to the body or clothing of the subject, whereby EKG signals from the patient can be monitored simply when a part of the patient's body is resting upon the sensor device.
Another object of the present invention is the provision of a novel EKG monitoring sensor in pad form having a pair of highly conductive flexible metallic panels arranged on a non-conductive waterproof sheet or carrier, adapted to obtain EKG signals transmitted by the subject through the medium of the subject's perspiration to the sensor device when the subject is seated upon the pad or a portion of the subject's body is resting upon the pad.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.